Choose the odd number: 17, 19, and 23 are primes. One number is composite. Identify the composite number.
Verbal Reasoning
Classification
Difficulty: Easy
Choose an option
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A17
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B19
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C23
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D27
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ENone of these
Answer
Correct Answer: 27
Explanation
Introduction / Context:Prime recognition again isolates the outlier.
Given Data / Assumptions:
- Candidates: 17, 19, 23, 27.
- Definition: prime vs composite.
Concept / Approach:Use small-prime divisibility tests (especially 3).
Step-by-Step Solution:
27 → 2+7=9 → divisible by 3 → composite (3^3).17, 19, 23 → not divisible by 2,3,5 → primes.Verification / Alternative check:Direct factorization: 27 = 3 * 9 confirms compositeness.
Why Other Options Are Wrong:They are prime.
Common Pitfalls:Assuming all odd numbers are prime.
Final Answer:27 is the odd number.